On Thu, 25 Feb 2021, Zhengyejian (Zetta) wrote:
>
>
> On 2021/2/24 19:19, Lee Jones wrote:
> > On Tue, 23 Feb 2021, Zheng Yejian wrote:
> >
> > > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > >
> > > commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
> > >
> > > Both Geert and DaveJ reported that the recent futex commit:
> > >
> > > c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> > >
> > > introduced a problem with setting OWNER_DEAD. We set the bit on an
> > > uninitialized variable and then entirely optimize it away as a
> > > dead-store.
> > >
> > > Move the setting of the bit to where it is more useful.
> > >
> > > Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > > Reported-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > > Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> > > Link: http://lkml.kernel.org/r/20180122103947.GD2228@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> > > Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
> >
> > Why have you dropped my Reviewed-by?
> >
> Really sorry. I thought that a changed patchset needs another review.
> Then I do need to append your Reviewed-by and send a "V2" patchset, Do I?
No need. I won't hold up merging just for that.
Just bear in mind that you should apply and carry forward *-by tags
unless there have been significant/functional changes.
Reviewed-by: Lee Jones <lee.jones@xxxxxxxxxx>
> > > ---
> > > kernel/futex.c | 6 +++---
> > > 1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/kernel/futex.c b/kernel/futex.c
> > > index b65dbb5d60bb..604d1cb9839d 100644
> > > --- a/kernel/futex.c
> > > +++ b/kernel/futex.c
> > > @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> > > int err = 0;
> > > oldowner = pi_state->owner;
> > > - /* Owner died? */
> > > - if (!pi_state->owner)
> > > - newtid |= FUTEX_OWNER_DIED;
> > > /*
> > > * We are here because either:
> > > @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> > > }
> > > newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
> > > + /* Owner died? */
> > > + if (!pi_state->owner)
> > > + newtid |= FUTEX_OWNER_DIED;
> > > if (get_futex_value_locked(&uval, uaddr))
> > > goto handle_fault;
> >
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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